A well-working implant for occluding a passage in a circulatory system is disclosed in WO 02/38051. This implant has its particular application as a cardiological implant by means of which it is possible, for example, to close an aperture through the atrial septum or the ventricle septum of a heart. It is arranged to be deployed or built up (i.e., assembled) at a desired location in the body (e.g. the heart), in contrast to known other implants (e.g. so-called umbrellas and sails) that are instead extended as soon as the compressed umbrella leaves its insertion sheath.
This implant includes a plurality of thin wire-like elongate members each having a proximal and a distal end and being made of non-bendable material. The implant further comprises two holders to which the ends of the elongate members are attached. By reducing the distance between the two holders the elongate members are caused to execute a twisting motion yielding in a plurality of radially extending loops. When the two holders are interlocked with each other, the loops are fixed in a fixation structure which fixes the implant in the passage.
The implant further comprises an occluding body being fixed to the elongate members. This occluding body is deployed or expanded when the two holders are brought together and the passage is closed. In one embodiment, a balloon structure is expanded on both side of the passage, e.g. the atrial septum. In another preferred embodiment, a disk-shaped occluding body made of a flexible material is arranged in the middle between the two holders and hold in its expanded position by the twisted elongate members.
One of the advantages of using a single occluding body implant is that only one occluding body has to be opened and placed in the passage. However, sometimes, the opening in the passage is such, that the occluding body is not big enough to securely close the passage. It is then preferred to locate an occluding body on both sides of the septum each.
Such an implant is shown in U.S. Pat. No. 5,171,259. It comprises a pair of patches each consisting of a resilient, foldable annular frame and a piece of cloth stretched over and fixed to the frame. The patches are so arranged as to face each other across a gap and sewed together concentrically with a thread slightly inwardly of the outer circumferential edge thereof in such a manner that as the thread is pulled the two patches are moved so as to approach each other. This implant is introduced into the passage using a catheter. First the first patch is released from the catheter and opened, then the catheter is retrieved a bit before the second patch is released and opened. U.S. Pat. No. 4,836,204 discloses an implant comprising two balloons, wherein they are also opened one after the other. These implants have the disadvantages, that two occluding bodies must be placed and opened in the passage at two different times during surgery.
U.S. Pat. No. 6,117,159 shows a catheter delivered device to close a septal defect, the implant comprising a shaft with concentric parallel cuts through the wall of the device which create flattened support struts. The centre of the support struts move radially away from the axis in a hinge like fashion in response to the movement of the device's proximal and distal ends toward the centre of the device. This device does not comprise an occluding body but it is coated with determinants which can improve tissue growth.